Liquid sequencing is a critical function in rotating analytical systems. Standard systems make use of active elements to open valves in order to perform sequential flow of liquids into predefined regions. One example of such an active valve implementation is described in WO2010084190. It would however be preferable to eliminate the use of active elements in order to simplify the manufacture and use of rotating analytical systems.
One way to perform liquid sequencing without using active elements includes using serial capillary siphons, with one example being described in patent application WO2008106782. However, this approach leads to significant complexity, since it implies adding one new fluidic structure and one stop in the rotation protocol for each new liquid to be added in the rotation sequence.
Therefore it would be advantageous to provide simplified liquid sequencing in rotating analytical systems, without active elements and without the need to introduce an increasing number of structures and operating functions when increasing the number of liquids to be sequenced.